Recently, automation of various examination such as laboratory tests and reduction of time for determination are attempted in hospitals, inspection institutions and the like in the light of shortage of manpower, cost reduction, a large quantity of samples to be treated, and the like. As a method suitable for such automation, attentions are drawn to an agglutination immunoassay, wherein an antigenic substance is determined by an agglutination reaction of insoluble carrier particles. For example, Japanese Published Unexamined Patent Application No. 35752/95 discloses an agglutination immunoassay which comprises allowing an antigenic substance in a sample to bind to insoluble carrier particles carrying substantially neither antigens nor antibodies thereon, and allowing an antibody or an antibody complex which reacts specifically to the antigenic substance to bind to the antigenic substance to give a selective agglutination of the insoluble carrier particles.
However, in an agglutination immunoassay, it is difficult to have a reaction with good reproducibility due to the non-uniformity of agglutination in an agglutination reaction of the insoluble carrier particles with antigens or antibodies. Specifically, in an agglutination immunoassay which comprises allowing an antigenic substance in a sample to bind to insoluble carrier particles carrying substantially neither antigens nor antibodies thereon, and allowing an antibody or an antibody complex which reacts specifically to the antigenic substance to bind to the antigenic substance to give a selective agglutination of the insoluble carrier particles, there are problems such as direct binding of antibodies to the insoluble carrier particles. Therefore, improvement of reproducibility in the agglutination immunoassay is required.
An object of the present invention is to provide: an agglutination immunoassay which comprises allowing an antigenic substance in a sample to bind to insoluble carrier particles carrying substantially neither antigens nor antibodies thereon, and allowing an antibody or an antibody complex which reacts specifically to the antigenic substance to bind to the antigenic substance to give a selective agglutination of the insoluble carrier particles due to stabilization and uniformization of an agglutination as well as prevention of non-specific adsorption; and a reagent therefor.